The present invention relates generally to vibration cancellation and more specifically to monitoring and testing and operator controlling of vibration cancellation systems.
Primary vibrations in gas liquid or solids have been cancelled or nullified, at least in part, with specially generated cancelling or secondary vibrations. For example, the prior art device shown U.S. Pat. No. 4,490,841 to Chaplin et al., specifically shows a method and apparatus for cancelling vibrations wherein a vibration sensor is connected through an input circuit and fourier transformer to a processor which produces an output through a fourier transformer and output circuit to a vibration actuator. A synchronous input is also provided to the processor from the vibration source. Although no adjustment, testing or monitoring is described in the aforementioned patent, a minimum amount of adjustment is available and includes generally the frequency bandwidth of the frequencies which the system is capable of handling, the gain of the amplifiers, and other types of adjustments. The only measure of the inability of the system to handle the particular environment is that the vibrations have not been effectively cancelled.
An automatic digital audio processor (ADAP) has been produced by Rockwell International, and is specifically described in an article by James E. Paul, "Adaptive Digital Techniques for Audio and Noise Cancellation", IEEE Circuits and Systems Magazine, Volume 1, No. 4, pp. 2-7. The ADAP specifically displays the convergence time, the sample time, the filter order and the input delay. These parameters, as well as bandwidth may be adjusted on this system. Neither an integral testor nor the display of many of the signals within the circuitry are provided in this article.
The prior art has failed to take advantage of the signals available within the electronics to provide monitoring of the operation of the circuitry as well as an indication of the operation of system in which the vibrations are being cancelled. If one can monitor these signals, they can determine whether the vibrations produced are normal, or if the vibrations indicate a serious failure of the system.
Thus, it is an object of the present invention to provide a monitoring system for a vibration cancellation system.
Another object of the present invention is to provide the capability to determine whether the systems whose vibrations are to be cancelled is operating in a safe range.
A further object of the present invention is to provide a monitoring system and display which may be integral with or separate from a vibration cancellation system.
A still further object of the present invention is to provide a display and input device for varying the operating parameters of the vibration cancellation system.
A still even further object of the present invention is to provide an integral testor for vibration cancellation systems which test the individual elements of the circuitry as well as their response.
These and other objects are obtained by providing a display for displaying one or more of the following: the input vibration signal received from the vibration system; the transfer function of the cancellation system; and the output vibration cancellation signal. The input circuit generates an input waveform from the input signals and provides an input spectral waveform to the transfer function generator. The transfer function generator provides an output spectral waveform which is converted by the output circuitry to a vibration cancellation actuator signal. The display displays the input signal waveform, the input spectral waveform, the transfer function, the output spectral waveform and the vibration cancellation actuator signal. The input and output circuits each include a peak detector and the display displays the peak of the respective input and output signals. The gain of the input circuit is self-adjusting and the display also displays the input gain. The average magnitude of the transfer function and the spectral waveform of the transfer function are also displayed.
Circuitry is also provided for the synchronization signal received by the vibration cancellation system to determine certain parameters and display them. A rate detector and period detector respectively detect a sample rate and sample period from the synchronization signal. The display displays the detected sample rate and sample period.
In the embodiment wherein the monitoring and display system is separate and distinct from the vibration cancellation system, the monitoring and display system receives the input and output vibration signals and the synchronization signals from the vibration cancellation system. In addition to displaying the input vibration signal and the output vibration cancellation signal, the monitoring and display system would also calculate the transfer function of the cancellation system as well as deriving the appropriate input and output spectral displays. Similarly, the synchronization data would also be determined within the monitoring and display system. It should also be noted that the operator control of the parameters of the vibration cancellation system and the test would not be included in the monitoring display system which is not integral with the vibration control system. In the case of the stand-alone monitor it should be noted that the tester may be part of the stand-alone monitor and the only element not provided is the display of operator controllable inputs and parameters.
An input device is provided for setting a maximum output signal level and minimum input signal thresholds and the display displays these values. The input device may also input the highest and lowest frequency or bandwidth of the signals to be processed and the display displays these two values. The zero reference value for the spectral waveform for the display may also be set and displayed. The system receives synchronization signals and displays a sample rate and revolutions per minute of the synchronization signal. The input device may provide input for the minimum revolutions per minute for which the transfer function will operate which is also displayed. Circuitry is provided to convert the input vibration signal, transfer function and output vibration signals from vibration cancellation format to display format. The display may be in a common housing with the input, output and transfer circuitry or may be separate therefrom and connected by a communication link.
The testing circuitry integral with the vibration cancellation and monitor system includes five testing modes. The first testing mode produces an output pulse and determines the frequency at which the maximum input occurs in response to the output pulse and then provides a single tone output pulse at that frequency. The second mode produces a single tone output signal at the frequency of the lowest frequency of the input signal which is preset. The third mode produces a variable harmonic pulsating output signal. The fourth mode delivers the input signal to the output circuitry bypassing the transfer circuit. The fifth testing mode disables the output circuitry. During all the test modes, the input signals and spectrum are displayed.
It should be noted that throughout the specification and claims the use of the word "circuitry" is considered generic, and are defined so as to include not only electronic elements to perform the functions described, but also processors with software capable of performing these functions. For example, the functions of the input, transfer and output circuitry could all be performed in software. Thus, the term "circuitry" is not to be considered limiting.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.